| It is well known that PbO2 as an anode material exhibits excellent conductivity,good chemical stability,anti-corrosion and has been widely used in many areas such as batteries,electrosynthesis and wastewater treatment.In this thesis,Ni/α-PbO2/β-PbO2 and nanoporous PbO2 films have been electrodeposited onto pretreated 304 stainless steel substrate.The surface morphologies,structures and eletrocatalytic activities of PbO2 films have been investigated with scanning electron microscopy(SEM),X-Ray power differaction(XRD)and electrochemical methodes.The main results as follows:The substrate is 0.25 cm2 304 stainless steel which has been pretreated with mechanically polishing,alkaline degreasing(5 wt%NaOH)at 60～70℃for 30 min and acid eroding(37%HC1)at 25℃for 10 min.1.Electrodeposition of Ni/α-PbO2/β-PbO2 film(1)The Ni layers were obtained from solutions containing 0.6 mol/L NiSO4.6H2O,0.6 mol/L H3BO3,0.3 mmol/L sodium lauryl fulfate,pH 4.0,at 45～60℃and 20 mA/cm2.The stainless steel and Ni were used as cathode and anode,respectively.(2)Theα-PbO2 layers were prepared in 3.5 mol/L NaOH+PbO(sat.), at 30℃and 10 mA/cm2(anodic).The Ni electrodeposits and Pt were used as anode and cathode,respectively.(3)Theβ-PbO2 layers were potentiostatly electrodeposited from solutions containing 0.6 mol/L Pb(NO3)2,0.4 mol/L HNO3,0.01 mol/L NaF,at 65℃and 1.6 V(vs.SCE).The Ni/α-PbO2 deposits and Pt were used as anode and cathode,respectively.The deposited time of various layers is within 60～1200 s.2.The surface morphologies,structures and electrochemical performance of Ni/α-PbO2/β-PbO2 filmsThe results of XRD showed that the texture of Ni/α-PbO2/β-PbO2 films is influenced by the interlayers of Ni,α-PbO2 and their deposition time.The results of SEM indicated that the morphologies of theβ-PbO2 films are dependent onα-PbO2/β-PbO2 or the types of interlayers Ni,α-PbO2,however, independent of the deposition time of the interlayers.In a solution of 1.0 mol/L H2SO4,the results of anodic polarization curves showed that activities of theβ-PbO2 for electrooxidation 4-methylpyridine are influenced by the type and deposition time of different interlayers.The best performance for 4-methylpyridine electrooxidation was observed on the Ni/α-PbO2/β-PbO2 prepared by electrodeposited Ni,α-PbO2 andβ-PbO2 for 300 s,240 s and 400 s,respectively.3.Electrodeposition of nanoporous PbO2 filmsNanoporous PbO2 films were first prepared under the high anodic polarization potentials on the substrats of the 304 stainless steel from a bath of 1～200 mmol/L Pb(NO3)2,0.4 mol/L HNO3 and 0.01 mol/L NaF.The results of SEM indicated that the electrodeposited parameters such as potential, concentration,temperature and deposition time influence on the formation of nanopores and the size of the pores.The results of XRD revealed that the phase presented in the nanoporous films isβ-PbO2.The results indicated that concomitant oxygen bubbles,originating from the surface of electrode at high anodic potential,played an important role during the formation of nanoporous PbO2 coatings.The nanoporous PbO2 films could be easily obtained by electrodepositing at 2.5～4.5 V(vs.SCE)for 3～20 s.The results of anodic polarization curves in 1.0 mol/L H2SO4+phenol showed that the performance of nanoporous PbO2 electrodes for electrodegradation phenol is better than that of nanoparticle PbO2 electrode without nanopores.
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